Please be advised that T-Mobile USA has reported an outage on their network effecting areas across the USA.

Our TK372/TK373 trackers with a managed SIM card might not be able to connect to servers to report tracking data today.
Your TK372/TK373 track should fall back automatically and connect to AT&T if signal on AT&T is available.
Otherwise you'll see tracking interruption (the tracker is able to cache the location data for a few hours and send them later when network connection recovers).

For other trackers that use T-Mobile SIM or other SIMs using T-Mobile network (for instance, US Mobile), you might see tracking interruption.

Update: T-Mobile has confirmed that a fiber wire cut has resulted in loss of all data roaming traffic.
They haven't given an estimate time for recovery. Our guess is that it may take hours to fix the fiber wire if there's no other fail-over lines.